Edit a document, copying part of it into the clipboard, and close it
git reset --hard
git log
No information
git fsck --lost-found
git reflog
5077fe4 - My latest commit
66b8889 - A previous commit
2b2c9e5 - An even earlier commit
git merge 5077fe4
git log
Back to original

Open the document again, pasting the clipboard in at the relevant point